Process and device for the formation of monofilaments produced by melt-spinning

Abstract

A continuous process and apparatus for the production of melt-spun monofilaments having a diameter of 60 μm to 2500 μm from fiber-forming polymers, wherein the polymer melt is spun into air from a spinning head, laterally quenched in a spinning cabinet with a defined air velocity profile and then cooled in a liquid bath.

We claim: 
     
       1. Continuous process for the production of monofilament fibers 23 having a diameter of 60 μm to 2000 μm from fibre-forming thermoplastic polymers by melt-spinning of the molten polymer from a spinning head 17, lateral quenching of the fibers 23 with cooling gas in a spinning cabinet 2, cooling of the formed fibers in a cooling liquid bath 5, removal of adhering cooling liquid 24, optionally applying a finish, stretching the fibers 23 in one or more stages, setting and winding the fibers 23 at a delivery speed of the set fibers 23 of 100 to 4000 m/min, wherein the cooling gas has a temperature of 0 to 50° C., the cooling gas exhibits a defined velocity profile which decreases in the running direction of the fibers and the cooling liquid has a temperature of -10 to 150° C. 
     
     
       2. Process according to claim 1, wherein the cooling gas flows from nozzles 20, which are arranged annularly around the fibers 23 in the spinning cabinet, into the spinning cabinet 2 and the cooling gas, together with the vapors released by the spun fibers 23, is exhausted below the nozzles 20. 
     
     
       3. Process according to claim 1, wherein the cooling gas enters through the quenching unit 3, which is arranged on one side of the spinning cabinet 2, and the cooling gas, together with the vapors released by the spun fibers 23, is exhausted opposite the unit 3. 
     
     
       4. Process according to claim 1, wherein the spinning cabinet 2 isolates the fibers 23 from their surroundings between the spinning head 17 and the liquid bath 5. 
     
     
       5. Process according to claim 1, wherein the spinning cabinet 2 has a length of 2 to 200 cm. 
     
     
       6. Process according to claim 1, wherein the air velocity in the spinning cabinet 2, measured transversely to the haul-off direction of the fibers 23, is 0.05 to 10 m/sec, at a distance of 0.5 to 6 cm from the spinneret 1. 
     
     
       7. Process according to claim 1, wherein the spinning gas velocity in the spinning cabinet 2 is 0.001 m/sec to 1 m/sec, at a distance of 6 to 200 cm from the spinneret 1. 
     
     
       8. Process according to claim 1, wherein the fibers 23 are quenched in the spinning cabinet 2 with temperature-controlled air of a temperature of 0 to 50° C. 
     
     
       9. Process according to claim 1, wherein the air introduced into the spinning cabinet 2, together with the vapors released by the spun fibers 23, is exhausted opposite the air inlet uniformly over the entire spinning cabinet 2. 
     
     
       10. Process according to claim 4, wherein exhausting produces a pressure differential of 10 to 100 Pa relative to ambient pressure in the spinning cabinet 2. 
     
     
       11. Process according to claim 1, wherein the fiber-forming polymer used is a polyamide, polyethylene terephthalate, polybutylene terephthalate, polypropylene or polyethylene. 
     
     
       12. Apparatus for the performance of the process according to claim 1 comprising a melt-spinning head 17 with a spinneret 1, a spinning cabinet 2 with a quenching unit 3 adapted to introduce cooting gas into the spinning cabinet and produce a cooling gas flow in said spinning cabinet having a velocity profile which decreases in the direction running from the spinning head to the liquid bath, an exhausting unit 4, a liquid bath 5 with fibre guides 6 and baffles 16, wipers 7 and an adhering liquid aspirator 9, optionally a spinning finish application station 10, one or more stretching units 12, a setting zone 14 and windup stations 15, wherein the spinning cabinet 2 surrounds the space between the spinning head 17 and surface 18 of the cooling liquid bath 5 in the area of the monofilaments 23. 
     
     
       13. Apparatus according to claim 12, wherein nozzles in the quenching unit 3 are arranged in the spinning cabinet 2 on one side to quench the fibers 23 and are provided with flow smoothers 21. 
     
     
       14. Apparatus according to claim 12, wherein the first nozzle of the quenching unit 3 in the spinning cabinet 2 below the spinneret 1 is an adjustable flat nozzle. 
     
     
       15. Apparatus according to claim 12, wherein all the nozzles of the spinning cabinet 2 are separately controllable to adjust the gas velocity of the nozzles in accordance with the required air flow profile. 
     
     
       16. Apparatus according to claim 12, wherein an annular nozzle with flow smoothers is provided in the spinning cabinet 2 as the quenching unit 3 for the fibers 23. 
     
     
       17. Apparatus according to claim 12, wherein an annular exhaust 22 is provided in the spinning cabinet 2, by means of which the air introduced into the spinning cabinet 2, together with the vapors released by the spun fibers 23, is exhausted below the nozzles. 
     
     
       18. Apparatus according to claim 12, wherein the spinning cabinet 2 contains cooling gas exhausts opposite the air inlet nozzles. 
     
     
       19. Process according to claim 5, wherein said length is 8 to 60 cm. 
     
     
       20. Process according to claim 6, wherein said air velocity is 0.1 to 2 m/sec. 
     
     
       21. Process according to claim 7, wherein said spinning gas velocity is 0.01 to 0.2 m/sec. 
     
     
       22. Process according to claim 8, wherein said temperature is 10 to 30° C. 
     
     
       23. Process according to claim 11, wherein said polymer is a polyamide.